"I don't want to get into [radar gun readings]," Melvin said. "We want to get him back to throwing strikes. ... We thought he was making some progress, but we want to make sure he's completely healthy and back to throwing strikes on a consistent basis."
Henderson is on his second 30-day Minor League rehabilitation assignment. He was recalled from the first one in May after the shoulder flared up again, and was sent back out on July 3 for another 30-day stint.
Melvin said another rehabbing reliever, Tyler Thornburg, who has been on the DL since early June because of a right elbow injury, is throwing off the mound in Arizona.
"We hope to get him back at some point [before the end of this season]," Melvin said.
The Brewers are closely monitoring the progress of both of those pitchers, who played prominent roles during the team's 20-8 March and April, as the July 31 non-waiver Trade Deadline draws near. The Angels made the first strike on the relief market Friday when they executed a six-player swap with the Padres to land closer Huston Street.
Asked whether the Brewers had checked in with the Padres on Street, Melvin said, "I check in on a lot of guys."
Much of the analysis of Friday's trade centered on the price paid by the Angels, who received Street for the rest of this season and all of next season and a relief prospect in exchange for four prospects, including one of Los Angeles' top prospects, Taylor Lindsey. Melvin pointed out that when the Brewers acquired setup man Scott Linebrink from the Padres in July 27, the price was three quality prospects.
"Relievers become costly for the few innings they pitch," Melvin said.
Adam McCalvy is a reporter for MLB.com. Read his blog, Brew Beat, and follow him on Twitter at @AdamMcCalvy. This story was not subject to the approval of Major League Baseball or its clubs.